Issues with regions, Family Sharing, and iTunes credit

I have reached quite the unfortunate situation. I wanted to set up Family Sharing with a couple of users, but it iTunes tells me that I cannot do that because I have no payment method set up. I have iTunes credit, but apparently that's not good enough for Apple.

So I tried to add a credit card, but my account is a US account, so I couldn't add my Colombian credit card.

Then I tried to switch countries on my account, but I couldn't because I still had credit left, and apparently I have to use it all up (over 70 dollars at this point), before I can switch accounts.

All I want is to be able to set up Family Sharing. I'd rather not have two different accounts, because that would screw up all the new Continuity features, and I have been using the same account for years now.

Any thoughts or suggestions?

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Related (and not very encouraging) question: How can I change iTunes country of region when having some credit in my account?